Conventionally, Patent Document 1 (International Patent Publication No. WO 0007836 A1) discloses regarding a vehicle air conditioner, which is provided with an evaporator of a refrigerant cycle as a cooling heat exchanger. The cooling heat exchanger is used for cooling air to be blown into a vehicle compartment. The vehicle air conditioner is made to prevent bad odor generation in the blown air at the evaporator.
Specifically, the air conditioner in Patent Document 1 controls a refrigerant discharge capacity of a compressor of the refrigerant cycle, such that an evaporation temperature of refrigerant flowing in the evaporator becomes higher or lower by a predetermined degree than a dew-point temperature of the blown air flowing into the evaporator. Accordingly, an outer surface of the evaporator is not dry and wet frequently. Therefore, bad odor generation in the blown air is prevented.
However, the bad odor generation in the blown air due to the drying of the outer surface of the evaporator may not be prevented just by setting the evaporation temperature of refrigerant flowing in the evaporator to be lower by the predetermined degree than the dew-point temperature of air flowing into the evaporator. For example, when the dew-point temperature of the blown air decreases drastically, or when a water-holding amount of the outer surface of the evaporator is small at a start of air conditioning of the vehicle compartment, the outer surface of the evaporator may become dry, and thereby bad odor may be generated in air to be blown into the vehicle compartment.
In response, it may be considered that the evaporation temperature of refrigerant flowing in the evaporator is made to be much lower than the dew-point temperature of air to be blown into the evaporator. However, in this case, consumed driving power of the compressor increases, and accordingly energy consumed in the whole air conditioner increases.